Apparatus and method for cutting holes in steel plates

ABSTRACT

Single or ganged cutting torches for steel plates preheat the center of each hole to be cut prior to any displacement of the torches. On completion of the preheating, the torches are laterally repositioned in correspondence with the common radius of the holes to be cut. Simultaneously, the torches begin to cut and motive means initiates and maintains circular movement of each of the torches commensurate with the circumference of the holes to be cut. Positioning means for locating each of the torches in the X-axis and for translating the torches en masse in the Y-axis are disclosed. Means for accommodating bowing of the steel plate along with means for setting the torches to cut various diameter holes at any bevel angle are described.

The present invention relates to cutting torches and, more particularly,apparatus for controlling movement of one or ganged cutting torches withrespect to a workpiece.

In most manufacturing facilities producing uniformly shaped, sized orapertured workpieces, machine controlled apparatus is employed toposition and guide one or ganged cutting torches in order to insurerepetitively uniform workpieces. U.S. Pat. No. 2,517,622 describes a setof ganged cutting torches for severing segments from a sheet of steel.U.S. Pat. No. 2,533,311 is directed to ganged cutting torches forcutting tapered or untapered workpieces of circular cross-section. U.S.Pat. No. 4,030,711 illustrates a plurality of cutting torches forsimultaneously cutting circles in a sheet of steel. In the apparatusdescribed in the above identified patents, all of the cutting torchesare ganged and none of them maintain a constant orientation to the axisof rotation. With this arrangement of the cutting torches, bevels canonly be cut along a straight cut line and all curved cuts must haveedges vertical to the major plane of the workpiece.

It is therefore a primary object of the present invention to provideganged cutting torches for cutting straight or constant beveled edgesirrespective of the degree of curvature of the cut line.

Another object of the present invention is to provide a means forindividually rotating each torch of ganged cutting torches about an axisof rotation simultaneous with rectilinear translation of the gangedcutting torches.

U.S. Pat. No. 3,547,424 is directed to a post mounted articulatedsupport structure for a cutting torch which translates the cutting torchin either of two axis in a workpiece in accordance with a predeterminedprogram. No provision exists for maintaining a constant bevel angle whena curved line is being cut.

Still another object of the present invention is to provide apparatusfor controlling the movement of a cutting torch which maintains aconstant beveled angle during translation of the cutting torch along acircular path.

Yet another object of the present invention is to provide means forcutting a constant bevel angle along a circular cut with an individualcutting torch or with ganged cutting torches.

U.S. Pat. Nos. 3,351,332, 3,591,156 and 3,701,515 are directed tovarious devices for cutting circular holes in a workpiece wherein acutting torch rotates about a point physically keyed to a predeterminedmark upon the workpiece and representative of the center of the circleto be cut. Means are also disclosed in U.S. Pat. Nos. 3,591,156 and3,701,515 for preventing twisting of the gas lines to the cutting torchwhile the torch rotates about the point. Prior to operation of any ofthe above described devices, the workpiece must be marked to locate thecenter point of the circle and the torch supporting apparatus must bephysically repositioned commensurate with the mark to engage a pointerwith the mark. Thereafter, cutting of the aperture may commence. Wherethe workpiece is to be dimpled to receive the pointer, a presuppositionmust be made that the workpiece is soft enough to be dimpled.

Yet another object of the present invention is to obviate the need forindividually marking the center of any aperture to be cut in aworkpiece.

A further object of the present invention is to eliminate the need forphysically keying an element of a cutting torch to a predeterminedlocation upon the workpiece.

A yet further object of the present invention is to eliminate the needto physically index the workpiece directly with a cutting torch.

U.S. Pat. Nos. 3,188,069 and 3,747,911 are directed to support apparatusfor a cutting torch which support apparatus is mounted upon theworkpiece itself and indexed thereto by a pointer positionally alignedwith a mark upon the workpiece. Necessarily, the workpiece must be of acertain minimum size to accommodate the cutting torch support apparatus.

It is therefore a further object of the present invention to providepositioning apparatus for a cutting torch which is useable for any sizedworkpiece.

U.S. Pat. No. 3,713,635 is directed to positioning apparatus for acutting torch which is clamped to a workpiece. The necessity forclamping the apparatus to the workpiece requires the workpiece to belarger than a predeterminable minimal size. Moreover, the requirementexists that the workpiece be supported in such a manner as toaccommodate the clamps.

A still further object of the present invention is to provide apparatusfor supporting a cutting torch which apparatus is independent of theworkpiece supporting means.

U.S. Pat. No. 4,021,025 describes a cutting torch supporting apparatuswhich is secured to a workpiece by magnets. The apparatus must belocated with respect to the workpiece by aligning a pointer extendingtherefrom with a mark previously located upon the workpiece.

The use of magnets, if strong enough, will maintain a cutting torchsupporting apparatus but the requisite strength for the magnets isproportional to the degree of difficulty in locating the apparatus in apredetermined position upon the workpiece.

A still further object of the present invention is to provide a meansfor indexing a cutting torch to each of a plurality of positions upon aworkpiece without direct reference to the workpiece itself.

A plurality of cutting torch support apparatus for various definedrequirements, sold under the mark "Bug•O Systems", are manufactured bythe Weld Tooling Corporations. Each of these apparatus have a parallelin one of the above identified patents.

All of the above described prior art systems initiate cutting by thetorch on the actual cut line itself. This produces a channel or scarringon the cut line and precludes a smooth surfaced cut.

It is therefore a yet further object of the present invention to developa smooth surfaced beveled cut in a workpiece.

In ore treatment plants, crushers are used to reduce the size of the orepieces prior to further treatment. Such a crusher includes a largediameter cylinder having an interior lining of a plurality ofreplaceable liner plates. The size and thickness of these plates mayvary, depending upon the size of the crusher and the type of ore beingcrushed. In example, the liner plates may be 1/2 inch thick, 13 inchesin width and 37 inches in length or one inch thick, 18 inches in widthand 26 inches in length. Because of the very abrasive nature of the orecoming in contact with the liner plates, the liner plates are made ofsteel identified as REM-500 which is next to the hardest steel known orof steel identified as VORTEN which is the hardest steel known.

Each of these liner plates is retained in place by countersunk boltsthreadedly engaging a receiver of the liner plate support structure.Countersinking of the bolts is necessary to preclude wear of the bolthead which would render it extremely difficult to loosen the bolts andreplace the liner plates. It is therefore necessary to form countersunkholes in each liner plate at predetermined locations uniform throughoutall of the plates to render them fungible with respect to one another.

Because of the hardness of the steel used for the liner plates, drillingof the holes is totally impractical. Therefore, the holes must be cutwith a cutting torch. The use of any conventional apparatus forsupporting the cutting torch which requires a dimple formed in thesurface of the liner plate by a counter point as an index is notpractical because the counter point could shatter before the dimple isformed. To use prior art torch supporting apparatus which ismagnetically attached to or clamped to a liner plate to locate thecutting torch with respect to a marked reference point is possible butextremely high labor costs per cut hole result because of thesubstantial amount of time necessary in aligning the apparatus andattaching it to the plate. Moreover, the requirement for such manualaligning increases the possibility of slightly misaligned holes. Shouldany liner plates with out-of-line or out-of-position holes be sent to anore treatment facility, substantial and extremely expensive down timewill result pending the arrival of further replacement liner plates asconventional tools can only be employed at great expense to force thefit of the liner plates or enlarge the holes to obtain mating of thecountersunk bolts with the threaded receivers.

The present invention describes apparatus for cutting one or morecounterbored holes through such liner plates simultaneously without theneed for marking or dimpling an index for each of the holes and providesan unscarred beveled surface for receiving the bolt head. The apparatusincludes one or more cutting torches mounted upon a translatablesupporting bar, the translation of which is commensurate with the radiusof the counterbore. Each cutting torch is mounted rotatable about anaxis of rotation without fouling the gas lines attendant thereto. Meansare incorporated in an underlying workpiece supporting platform forindexing each workpiece with respect to a single or ganged cuttingtorches. The latter being positionable along a scale upon the supportingbar, which scale is keyed to the workpiece indexing means. Translationof the supporting bar along the Y-axis for each of one or more distanceswithout skewing of the supporting bar is also provided. Since it is notuncommon for a workpiece to be slightly bowed, means are provided foraltering the height of the cutting torch to accommodate such bowing andprovide correctly sized and located holes. Means are also provided foradjusting the cutting torches to differently sized holes, to accommodatedifferent plate thicknesses and to accommodate a range of bevel angles.

In operation, the cutting torches are placed in a heating mode topreheat the center of the hole to be cut. After a predetermined time,the torches are switched to a cutting mode. Simultaneously, each of thetorches begins to rotate about its respective axis and the supportingbar is translated for a distance commensurate with the radius of theholes to be cut. The resulting cut represents a spiral melding smoothlyinto a beveled edge defining the perimeter of the hole extending throughthe plate.

The present invention may be described with further specificity andclarity with reference to the following drawings, in which:

FIG. 1 is an elevational view of cutting torches located above aworkpiece by a supporting superstructure;

FIG. 2 illustrates the configuration of the cut;

FIG. 3 is a cross-sectional view of a cut hole;

FIG. 4 is a cross-sectional view taken along lines 4--4, as shown inFIG. 1;

FIG. 4a is a cross-sectional view taken along lines 4a--4a, as shown inFIG. 4;

FIG. 5 is a cross-sectional view taken along lines 5--5, as shown inFIG. 1;

FIG. 6 is a partial isometric view illustrating a part of the transportapparatus;

FIG. 7 is a cross-sectional view taken along lines 7--7, as shown inFIG. 6;

FIG. 8 is a cross-sectional view of the rotary couplings supporting thecutting torch;

FIG. 9 is a cross-sectional view taken along lines 9--9, as shown inFIG. 8;

FIG. 10 is a cross-sectional view taken along lines 10--10, as shown inFIG. 8;

FIG. 11 is an end view taken along lines 11--11, as shown in FIG. 8;

FIG. 12 is a partial elevational view illustrating indexing of thecutting head to the workpiece;

FIG. 13 is an end view taken along lines 13--13, as shown in FIG. 12;

FIG. 14 is a schematic diagram of the control circuitry; and

FIG. 15 is a legend in reference to FIG. 14.

FIG. 1 illustrates the apparatus for supporting, operating andtransporting a ganged pair of cutting torches with respect to an indexedworkpiece. A robust frame 10 includes a platform 12 upon which aworkpiece 14 is placed. The platform may include a plurality oflaterally supported rails 16 to give adequate support and yet provideopen bays directly beneath any holes to be cut in the workpiece toprevent damage to the platform by the cutting torches. Workpiece 14 isindexed to platform 12 by index means, such as block 18 disposed alongone edge of the workpiece and blocks 20, 22 disposed along another edgeof the workpiece. Maintenance of the workpiece adjacent the blocks maybe effected by clamps 24, 26.

A superstructure 30 supports cutting torches 32, 34 along with therotational drive means 36, 38 associated with each torch and controlpanel 40. The superstructure is translatable in the Y-axis (rearwardlyand forwardly) by grooved wheels collectively referenced by numeral 42,engaging rails 44 and 46, which rails are rigidly attached to frame 10.The complementary pairs of the grooved wheels are mounted withindepending leg sections 48, 50, and rotationally locked together by acommon journal. The leg sections also include the mechanical positioningmeans for accurately locating the superstructure in the Y-axis andlocking means for maintaining the superstructure in place.

A manifold 28, which may be attached to a superstructure 30 or to frame10 provides oxygen at two different pressures and acetylene to thetorches through discrete flexible hoses and attendant couplings. Valvemeans are also incorporated attendant the manifold and under control ofthe switches on the control panel.

Rotational drive means 36 will be described in detail, but it is to beunderstood that rotational drive means 38 is a duplicate thereof. Therotational drive means includes a rotary coupling 52 having a block 53for receiving inputs 54, 55, 56 connected to three discreet sources ofgas by flexible couplings 57, 58 and 59, respectively. Outputs 60, 61and 62 are mounted upon a rotatable spindle 64 and are in fluidcommunication with the respective ones of flexible lines 65, 66 and 67.Spindle 64 supports cutting torch 32 through positioning means 72 whichpermits lateral repositioning of the cutting head with respect to theaxis of rotation of the spindle. The positioning means also includesangular adjustment means 74 for setting the angle of the cutting torchat any angle within a given range of angles. Electric motive means 76 isactuatable to rotate spindle 64 through a gear box 78 and coupling 80.

From the above description, it will become apparent that rotationaldrive means 36 may be actuated to effect rotational movement of cuttingtorch 32 about the axis of rotation of spindle 64 to cut a hole havingany bevel angle within a range of angles and of any radius within arange of radii. Moreover, fouling of the flexible lines conveying thevarious gases to the cutting torch will not result irrespective of thenumber of consecutive revolutions of the cutting torch in a givendirection.

The mounting of each of the rotational drive means upon super structure30 will be described with joint reference to FIGS. 1 and 5. Superstructure 30 includes a rigid robust square tube 90 which serves as asupporting bar and bears the load placed thereon without any perceptibleflexing. The tube is rigidly attached to leg sections 48 and 50 (seealso FIG. 4) by nut and bolt means. A member 92 extends along two joinedorthogonal sides of tube 90 and is in contact therewith through rollers94 and 96, which rollers permit relatively easy translation of themember along the tube. A further roller 98 is in frictional contact withthe rear vertical surface of tube 90. This roller is mounted upon ashaft 100 journaled within member 92 and supporting a handwheel 102.Through the restraints provided by these rollers against rotation ofmember 92 about the longitudinal axis of tube 90, such rotationalmovement of the member is precluded. A pedestal 104 is attached tomember 92 and supports electric motive means 76. Rotary coupling 52 isattached to member 92 directly by bolt 106 and by bolt 108 engaging arm110 extending from the rotary coupling. Thereby, rotational drive means36 is rigidly and robustly attached to member 92.

The member also includes an apertured ear 112 for engaging a penetratingrod 114. A thumb screw 116 is employed to lockingly engage the rod withthe ear. As will be described in further detail below, rod 114 istranslated along its longitudinal axis to reposition each of the cuttingtorches secured thereto in response to relative movement between member92 and tube 90 along the longitudinal axis of the tube.

As illustrated in FIG. 1, a scale 118 is attached to tube 90 along itsfront side. An index 120, which may be the edge of member 92, cooperateswith the scale to locate the axis of rotation of spindle 64 theindicated distance from the edge of the workpiece bearing against block18. Thereby, the location of the holes to be formed in the workpiecewith respect to the X-axis are settable by loosening thumb screw 116 andrepositioning rotational drive means 36 (and 38) to the desired value.Such repositioning may be effected by manually turning handwheel 102 tobring about rotation of roller 98 along the engaged side of tube 90. Thefriction intermediate the roller and the tube will result in movement ofmember 92 and the elements supported thereon. Thereby, very accurateindexing of the rotational drive means along scale 118 may beaccomplished. Thereafter, the rotational drive means is locked in placewith respect to rod 114 by tightening thumb screw 116. It is to beunderstood that other indexing means may be employed in the alternative.

Referring jointly to FIGS. 1, 4 and 4a, the means for translating thecutting torches in the X-axis during the cutting of the holes will bedescribed. A member 120, similar in configuration to member 92, issupported upon tube 90 by rollers 122 and 124. The member supports ajournaled shaft 126. A roller 128 is fixedly attached to one end of theshaft and bears against the rear surface of tube 90. Electric drivemeans 130 is mounted upon a pedestal 132 secured to and extendingupwardly from member 120. The other end of shaft 126 is operativelyattached to the armature of electric drive means 130 through a gear box134. An apertured ear 136 extends from member 120. Rod 114 is fixedlyattached to the ear to preclude translation of the rod along itslongitudinal axis with respect to the ear. A counterweight 138 issuspended from arm 140 extending from member 120 to bias roller 128against tube 90 which bias and hence frictional engagement may be variedby altering the weight of the counterweight or its position along arm140.

From the above description, it will become evident that upon actuationof electric drive means 130, roller 128 is caused to rotate. Rotation ofthis roller, due to its frictional engagement with the adjacent side oftube 90, will bring about translation of member 120 along thelongitudinal axis of tube 90. Such translatory motion results inequivalent translatory motion of rod 114. As described earlier, rod 114is fixedly secured to each of the rotational drive means and therotational drive means will be translated in ganged fashion along withtranslation of member 120. As illustrated particularly in FIG. 4a, limitstops 142 and 144 extend from tube 90 to limit the translationalmovement of member 120.

Translation of superstructure 30 in the Y-axis will be described withjoint reference to FIGS. 1, 4, 6 and 7. A toothed rack 150 is mountedupon frame 10 adjacent and parallel to rail 44 on the right-hand side ofthe frame, as viewed in FIG. 1. A similar toothed rack 150 is mountedadjacent rail 46 on the left hand side of the frame. A sprocket 152 isconcentrically mounted to each of grooved wheels 42 through countersunkAllen-head bolts 154. The sprocket engages the teeth in rack 150. Thecombination of grooved pulley and sprocket is rotatably mounted via ashaft within clevis-like keeper 158 extending downwardly from legsection 48. While the above description has been primarily directed tothe left front grooved wheel and sprocket combination, it is to beunderstood that each of the remaining grooved wheel and sprocketcombinations are similarly constructed and operate in the same manner.To prevent the skewing of superstructure 30, a shaft 160, lockinglyengages each of the opposed front grooved wheel and sprocketcombinations to preclude independent rotation therebetween. Similarly, afurther shaft 162 interconnects the opposed rear grooved wheel andsprocket combinations to preclude independent rotation therebetween.

The positioning of superstructure 30 in the Y-axis must be set withreference to the indexed workpiece and the location of the holes to beformed therein. A scale 164 is mounted upon frame 10 parallel to rack150 (see FIG. 6). An index 166 is attached to and extends downwardlyfrom leg section 48 into close proximity with the scale. The positionalrelationship of the index to the leg section is a function of therelative spacing between the indexed workpiece, the cutting torches,tube 90 and the location of the tube with respect to the leg section.Locking means (not shown specifically) is employed to lock thesuperstructure in the Y-axis. Stops, such as stop 168 may be employed toprevent inadvertent derailment of the grooved wheels from the supportingrails.

Referring jointly to FIGS. 8, 9 and 10, rotary coupling 52 will bedescribed. A block 53 includes a passageway 172 formed therein forrotatably receiving section 174 of spindle 64. The block includes aplurality of internal annular grooves 175, 176 and 177 in fluidcommunication with inlets 54, 56 and 55 via partially threadedpassageways 178, 179 and 180, respectively. Three longitudinally alignedpassageways 181, 182 and 183 are disposed within section 174. Each ofthese passageways is in fluid communication with one of the annulargrooves through the respective one of lateral passageways 184, 185 and186. Gas leakage intermediate the annular grooves is prevented by aplurality of O-rings 187, 188, 189 and 190 disposed within individualannular grooves in block 53 and bracketing annular grooves 175, 176 and177. To facilitate rotation intermediate section 174 and block 53,bearings 191 and 192 are employed.

Outputs 60, 61 and 62 extending from section 174 are in fluid engagementwith passageway 183, 182 and 181, respectively. Thereby, the gases fromflexible lines 57, 58 and 59 are transmittable to respective ones offlexible lines 65, 66 and 67 without entangling the lines when thecutting torch is rotated about the rotational axis of the rotationaldrive means.

To accommodate height adjustment of torch 32, spindle 64 includes aslidably adjustable sleeve 196 longitudinally adjustable with respect torod 198 by means of a thumb screw 200 threadedly engaging a shaft 202extending through a slot 204 in the sleeve. The lower end of the sleeveis affixed to and supports positioning means 72; the positioning meansincludes a slot 208 disposed therein for receivingly engaging bar 206.The bar includes a scale 210, which scale, in combination with an indexsuch as an edge of the positioning means, provides an indication of thelateral extension of cutting torch 32 from the axis of rotation. A thumbscrew 212 retains the bar secured within slot 208.

Referring jointly to FIGS. 8, 11, 12 and 13, the apparatus for securingand adjusting cutting torch 32 will be described. The cutting angle ofthe cutting torch is established by the angle set upon tightening of thejoint at angular adjustment means 74 intermediate bar 206 and collar216. The height of the tip of the torch above the surface of theworkpiece is variable by means of a handwheel 218 turning a ratchet 220frictionally cooperating with the barrel of the cutting torch. Once theposition of the cutting torch within the collar has been established, itis secured in place by thumbscrew 222 extending through the collar intofrictional contact with the barrel of the cutting torch.

To positionally align the axis of rotation of each rotational drivemeans with the center of any hole to be cut, tool 230 is employed. Thetool includes a magnet 232 disposed intermediate plates 234 and 236. Asparticularly illustrated in FIG. 13, the positional relationship betweenthe magnet and the plates is such as to partially receive a section ofsleeve 196 intermediate the plates in physical contact with the magnetand the edges of the plates. Thereby, the tool is repetitively andaccurately alignable with the spindle. An L-shaped member 238 extendsdownwardly and laterally and supports a downwardly extending pointer240. The physical location of pointer 240 with respect to the laterallyextending part of L-shaped member 238, in combination with thepositional relationship of magnet 232 to sleeve 196 is such as to alignthe axis of pointer 240 with the axis of rotation of spindle 64. It maybe noted that the vertical height of tool 230 may be varied toaccommodate different height positions of spindle 64. It will thereforebe evident that the rotational drive means supporting spindle 64 may bereadily set through use of the tool to obtain correct alignment with thecenter of the hole to be cut.

Usually, when a series of beveled holes are to be cut, as in the linerplates discussed above, a large number of constant diameter holes havingconstant bevel angles are needed. In such cases, a jig 250 is employed,which jig has a sloping side 252 commensurate with the bevel angle to becut. To set and periodically check the angle of cutting torch 32, side252 of the jig is brought against side 254 of collar 216, which side isparallel to the axis of the cutting torch. Any variation between side254 and side 252 would indicate angular misalignment and requireresetting of the angular adjustment means. To insure that cutting torch32 is at the proper height above the workpiece (and thereby accommodatebowing of the workpiece) to obtain optimum cutting capability of theemitted flame, a platform 256 is provided in jig 250. The height ofplatform 256 defines the height of tip 258 of cutting torch 32 above theworkpiece. Thereby, an initial setting and subsequent rechecks of thecorrect height of tip 258 can be accomplished by sliding platform 256thereunder. If the tip is to high, operation of ratchet 220 throughhandwheel 216 readily lowers (or raises) the tip and it may be relockedin the altered position by thumbwheel 222.

Referring to FIGS. 1, 2 and 3, the path defined by the cutting torchduring operation of the present invention will be described. Two of theflexible couplings conveying gas to each of the torches contain oxygen;in one of the lines, the oxygen is approximately 30 psi while in theother line, the oxygen is at a pressure in the range of 65 to 85 psi.The third line conveys a gas such as acetylene at approximately 7 to 9psi. After workpiece 14 has been placed upon platform 12 and properlyindexed and assuming the rotational drive means has been located at theappropriate X and Y coordinates, one of the switches on control panel 40is actuated. Thereupon, acetylene and low pressure oxygen will flow fromthe cutting torches and the flame, after ignition of the gases, willheat the center of the holes to be cut. After sufficient heat builduphas been achieved, a further switch is actuated to introduce highpressure oxygen to the cutting torches. The high pressure oxygen, incombination with the acetylene, begins to make a cut through theworkpiece. Simultaneously, electric drive means 130 is energized whichresults in translation of rod 114 to reposition each of the attachedganged rotational drive means along the X-axis for a distance equivalentto the radius of the hole to be cut. Also simultaneously, the electricmotive means of each rotational drive means is energized to rotate therespective spindles resulting in commensurate rotation of the attachedcutting torch.

The cut actually made is illustrated in FIG. 2. The simultaneous lateraltranslation of the rotational drive means coupled with rotation ofspindle 64 results in a spiral cut 260. The spiral terminatescommensurate with engagement of member 120 (see FIG. 4a) with limit stop142 which prevents further translation of rod 114 and furthertranslation of the ganged rotational drive means. Thereafter, thecontinuing rotation of the cutting torch due to the continuing actuationof the electric motive means produces a circular cut 262 at a bevelangle θ (see FIG. 3) commensurate with the angle at which the torch isset. By control signals established through circuitry and apparatusforming a part of the control panel, the deactuation of electric motivemeans 76 will occur on completion of cut 262.

Since the cut is not initiated along cut 262, the final beveled surface,the scarring or gouging attendant prior art devices will not result.Therefore, the surface of the beveled edge is extremely smooth and needsno finishing.

On completion of the various cut holes in workpiece 14, it may, in somecases, be prudent to size the beveled hole at the apex. To effectsizing, along with removal of any slag which may be weakly attachedthereto, a bolt or other reamer of appropriate dimension may be driventhrough the cut. Preferably, such sizing is performed while theworkpiece materials adjacent the hole is in a semi-molten state.

Referring to FIG. 14, there is illustrated a representative schematicfor the present invention wherein three rotational drive means areganged. The details and operation of the schematic need not be expoundedupon as the operation thereof will be evident to those skilled in theart of control systems when reference is made to the legend identifiedas FIG. 15.

While the present invention is structured to cut holes in steel plates,it may also be used for other purposes without any structuralmodifications. In example, a sheet of steel may be placed upon theplatform and cut into a plurality of pieces, such as the linear plates.The cutting attendant thereto is accomplished in one direction bytranslating the superstructure in the Y-axis. The cutting in the otherdirection is accomplished by translating the cutting torches along tube90 in the X-axis.

Moreover, it is to be understood that the liner plates can be cut from acommon sheet of steel and approximately apertured without the need forany ancillary equipment and without the need for handling except toplace the sheet of steel on the platform and remove the finished linerplates.

While the principles of the invention have now been made clear in anillustrative embodiment, there will be immediately obvious to thoseskilled in the art many modifications of structure, arrangement,proportions, elements, materials, and components, used in the practiceof the invention which are particularly adapted for specificenvironments and operating requirements without departing from thoseprinciples.

I claim:
 1. Apparatus for cutting an aperture in a workpiece with acutting torch, said apparatus comprising in combination:(a) rotationaldrive means for rotating the cutting torch about an axis of rotation tocut the perimeter of the aperture, said rotational drive means includinga block, a spindle rotatably mounted within said block, electric motivemeans for rotating said spindle, said spindle including a verticallypositionable sleeve slidable along the axis of rotation of said spindleto adjust the height of the cutting torch and a lock means for lockingsaid sleeve in place with respect to said spindle; and (b) translatingmeans for translating said rotational drive means rectilinearly apredetermined distance with respect to the workpiece during an initialrotational movement of the cutting torch, the joint operation of saidrotational drive means and said translating means acting upon thecutting torch to define a spiral cut made from a point interior of theperimeter of the aperture to the perimeter of the aperture.
 2. Theapparatus as set forth in claim 1 including positioning means forpositioning the cutting torch radially with respect to the axis ofrotation of said rotational drive means.
 3. The apparatus as set forthin claim 2 wherein said positioning means includes angular adjustmentmeans for adjusting the angle of the cutting torch and set the bevelangle of the cut made by the cutting torch.
 4. The apparatus as setforth in claim 3 wherein said angular adjustment means operates toadjust the angle of the cutting torch with respect to the axis ofrotation.
 5. The apparatus as set forth in claim 4 including a jiglocatable upon the workpiece for checking the angle of the cuttingtorch.
 6. The apparatus as set forth in claim 5 wherein said jigincludes means for checking the height of the tip of the cutting torchabove the surface of the workpiece.
 7. The apparatus as set forth inclaim 1 including a manifold and attached flexible lines for providing asource of various gases under pressure to the cutting torch through saidflexible lines and wherein said rotational drive means includes a rotarycoupling for channeling the gases from said flexible lines to thecutting torch.
 8. The apparatus as set forth in claim 1 including a toolfor depicting the axis of rotation of said spindle relative to theworkpiece, said tool being detachably attachable to said rotationaldrive means.
 9. The apparatus as set forth in claim 8 wherein said toolincludes a magnet and guide members for attaching and aligning said toolwith said spindle.
 10. The apparatus as set forth in claim 1including:(a) a frame, said frame including:i. a platform for supportingthe workpiece; ii. index means for indexing the workpiece on saidplatform; (b) a superstructure for supporting the cutting torch withrespect to the workpiece; (c) means for supporting said rotational drivemeans upon said superstructure; (d) means for locating said rotationaldrive means along the axis of said superstructure, which axiscorresponds to the X axis of the workpiece; (e) means for transportingsaid superstructure relative to said platform in an axis correspondingto the Y axis of the workpiece; (f) a control panel for controlling theoperation of said rotational drive means, said translating means and thecutting torch; and (g) a manifold assembly for supplying gases to thecutting torch.
 11. The tool as set forth in claim 10 wherein said toolincludes a plurality of ganged ones of said rotational drive means forsimultaneously cutting at least one aperture in the workpiece, each ofsaid rotational drive means supporting a cutting torch and providingrotational movement to the cutting torch about an axis of rotation andwherein said translating means translates all of said ganged rotationaldrive means as a unit.